The present disclosure relates to a cleaning mechanism for cleaning a photosensitive drum, and an image forming apparatus incorporated with the same.
An image forming apparatus as exemplified by a copier, a printer, a facsimile machine or a complex machine having the functions of these devices is provided with a cleaning mechanism for removing matter adhered to the surface of a photosensitive drum therefrom. In the case of a photosensitive drum using e.g. an amorphous silicon(a-Si)-based material, the drum surface is hard. Therefore, it is difficult to scrape off the matter adhered to the drum surface even by contacting a cleaning blade made of a resin with the drum surface.
In view of the above, as a conventional art, for removing matter adhered to the drum surface by contact, there has been proposed a cleaning mechanism including a rubbing roller which is pivotally pressed against a photosensitive drum, and a toner amount restricting plate which is contacted with the rubbing roller while pivotally moving coaxially with the rubbing roller.
In the cleaning mechanism, toner transported via e.g. a photosensitive drum is adhered to the surface of the rubbing roller. The rubbing roller is allowed to remove the matter adhered to the surface of the photosensitive drum by being contacted with the surface of the photosensitive drum, with use of the toner adhered to the surface of the rubbing roller as an abrasive agent. The toner amount restricting plate is contacted with the rubbing roller with a predetermined amount of bite|[K1] for adjusting the amount of toner on the surface of the rubbing roller to a proper amount.
The toner amount restricting plate is fixed to a bracket that is fixed to bearings of the rubbing roller. The bracket has bearing holding portions for holding the bearings, a toner amount restricting plate positioning portion for positioning the toner amount restricting plate in contact with a lower end of the toner amount restricting plate, and a toner amount restricting plate fixing portion for fixing the toner amount restricting plate positioned by the toner amount restricting plate positioning portion by a hot-melt process or a like process. The bearing holding portions, the toner amount restricting plate positioning portion, and the toner amount restricting plate fixing portion are formed into a one-piece member by bending a metal sheet or a like member.
More specifically, a metal sheet is bent at a portion (first bent portion) between the bearing holding portion and the toner amount restricting plate positioning portion, and is bent at a portion (second bent portion) between the toner amount restricting plate positioning portion and the toner amount restricting plate fixing portion. Thus, there are two bent portions between the bearing holding portion and the toner amount restricting plate fixing portion.
In the bracket of the cleaning mechanism as constructed above, a positioning surface of the toner amount restricting plate positioning portion which continues from the bearing holding portion via the first bent portion is defined as reference attachment position of the toner amount restricting plate. Further, the toner amount restricting plate is attached to an attachment surface of the toner amount restricting plate fixing portion which continues from the bearing holding portion via the first and second bent portions.
In the above configuration, in the case where the bending angle of the attachment surface varies within the dimensional tolerance in e.g. forming the bracket, the amount of bite of the toner amount restricting plate greatly changes with respect to the rubbing roller. As a result, the ability of restricting the toner amount (toner transport amount) on the surface of the rubbing roller, in other words, a toner restricting force may be unstable depending on the toner amount restricting plate.
For instance, in the case where the toner restricting force is weak because the amount of bite of the toner amount restricting plate is small, the amount of toner adhered to the surface of the rubbing roller i.e. a so-called toner transport amount on the surface of the rubbing roller increases, which causes drawbacks such as toner drop or formation of pinholes. On the other hand, in the case where the toner restricting force is strong because the amount of bite of the toner amount restricting plate is large, the toner transport amount on the surface of the rubbing roller is small. As a result, the abrasive force may be insufficient, which may cause drawbacks such as image blurring or wearing of the cleaning blade.
Further, in the above configuration, the toner amount restricting plate is attached to the toner amount restricting plate fixing portion which continues from the bearing holding portion via the two bent portions. As a result, it is difficult to sufficiently secure the area for the attachment surface of the toner amount restricting plate fixing portion, and the toner amount restricting plate may be peeled off from the toner amount restricting plate fixing portion if the toner amount restricting plate is attached to the toner amount restricting plate fixing portion by ordinary adhesive means such as a double-sided adhesive tape. This necessitates use of a process such as a hot-melt process capable of providing a strong adhesive force for preventing peeling off of the toner amount restricting plate, and may affect the number of assembling steps.
In view of the above, an object of the present disclosure is to provide a cleaning mechanism capable of suppressing variation in the amount of bite of a toner amount restricting plate, while enhancing the assembling workability, and an image forming apparatus provided with the same.